[mythtv-users] XvMC on NVidia with Myth .20 (Anyonegetting goodHD off a P4 3

R. G. Newbury newbury at mandamus.org
Mon Jan 8 21:39:18 UTC 2007

Drew Bernat wrote:
> On Jan 8, 2007, at 1:23 PM, R. G. Newbury wrote:
>> Right. Your "HDTV" cards will only do 'HD' if they are fed an HD
>> definition signal. Generally, that means OTA with an antenna or you are
>> in the US, where you can get unencrypted HD over cable for local (OTA
>> avilable) channels. If you are getting encrypted HD, then the output
>> form the STB is either by firewire or S-video, and in either case, will
>> not use your HD card to tune the signal.
> Right - I'm getting OTA HD. Sorry about not being specific.
>> Whoa... XVMC is explicitly a video card driver thingy. It has NOTHING to
>> do with the tuners. XVMC makes use of the video card *hardware* to do
>> stuff which would otherwise be done by the main CPU is producing the
>> video output. Which is why you see discussions of the computer power
>> needed to decode HD. You need either a pile of computer grunt, OR an
>> Nvidia or VIa video chipset which supports XVMC.
> Right. However:
> HD-resolution show recorded via HD tuner card: XvMC works
> SD-resolution show recorded via HD tuner card: unknown
> SD-resolution show recorded via SD tuner card: XvMC doesn't work
> This leads me to believe there is something about the _recording format_ 
> off the card that causes XvMC assistance to break, and not the inherent 
> resolution of the program. That's what I mean by tuner difference - 
> that's basically the only varying component right now.
I seriously doubt that your SD tuner card is doing anything which turns 
off XvMC unless you have done interesting things in mythtv... and fi you 
are at that level you would not be asking the questions, you would be 
giving the answers.

In myth the decoding method is set up Mythfrontend -> Setup ->Setup -TV 
Settings - > Playback (first page: Standard Decoder)

You can check your /var/log/Xorg.0.log file to see whether XVMC is 
properly initialized. There are also mentions in the mmythfrontend log 
output IIRC. More easily, you can run glxinfo which will tell you about 
the video drivers installed and used.

If you are worried that the card is not working, then look at dmesg and 
look for the IVTV START and IVTV END lines, since your PVR500 requires 
IVTV to work at all.


More information about the mythtv-users mailing list